PCA9530 2-bit I2C LED Dimmer

The PCA9530 is a 2-bit I2C and SMBus I/O expander optimized for
dimming LEDs in 256 Discrete steps for Red/Green/Blue (RGB)
color mixing and back light applications.
The PCA9530 contains an internal Oscillator with two user
programmable blink rates and duty cycles coupled to the output
PWM. The LED brightness is controlled by setting the blink rate high
enough (> 100 Hz) that the blinking CAN not be seen and then using
the duty cycle to vary the amount of time the LED is on and thus the
average current through the LED
The initial setup sequence programs the two blink rates/duty cycles
for each individual PWM. From then on, only one command from the
bus master is required to turn individual LEDs ON, OFF, BLINK
RATE 1 or BLINK RATE 2. Based on the programmed frequency
and duty cycle, BLINK RATE 1 and BLINK RATE 2 will cause the
LEDs to appear at a different brightness or blink at periods up to
1.69 second. The open drain outputs directly drive the LEDs with
maximum output sink current of 25 mA per bit and 50 mA per
package.
To blink LEDs at periods greater than 1.69 second the bus master
(MCU, MPU, DSP chipset, etc.) must send repeated commands to
turn the LED on and off as is currently done when using normal I/O
Expanders like the Philips PCF8574 or PCA9554. Any bits not used
for controlling the LEDsCAN be used for General Purpose Parallel
Input/Output (GPIO) expansion which provides a simple solution
when additional I/O is needed for ACPI Power SwitchesSensors
pushbuttons, alarm monitoring, fans, etc.
The active LOW hardware reset pin (RESET) and Power-On Reset
(POR) initialize the Registers to their default state causing the bits to
be set HIGH (LED off).
One hardware address pin on the PCA9530 allows two devices to
operate on the same bus.
By NXP Semiconductors